Erosion

Riverbank Erosion

Riverbank erosion is possible at any riverbank site. Past records of erosion or lack of erosion are not good indicators of the potential for future erosion at any particular site. Records of riverbank erosion are not kept but past aerial photographs may give an indication of past erosion. Long serving staff will have knowledge of some historical erosion sites.

Adjoining property owners are responsible for any work to prevent or repair riverbank erosion unless either

• A community scheme or rating district has been established to manage such works or
• A utility operator would receive such benefit from undertaking works that they elect to fund part or all the work.

Environment Canterbury has records of the properties which are within river rating districts and the level of rating applicable to each class in each district.

Wind Erosion

A risk of wind erosion occurs on Canterbury's arable soils when they are cultivated. Wind erosion of the soil depends on several factors interacting together before it will occur. Good farm management practices are available which will lower the risk of wind erosion occurring.
It is not possible to classify a risk of wind erosion at a property level without a site survey and professional interpretation of local soil and climatic factors and management practices.
Environment Canterbury has some information and historic survey results which could assist an assessment of wind erosion risk.

Slope Instability

Slope instability can lead to a number of forms of land movement or erosion:

• Mass movement such as, earth flows, land slip, slumps.
• Fluvial movements such as, tunnel gullies, gully erosion.

The stability of a slope is governed by slope, soil type, moisture and runoff control, vegetation type and condition and land management.

Base resource data in the form of land inventory and land capability maps were produced in the period 1960 - 1990 for many hill and high country properties. This mapping is at a scales ranging between 1:10,000 and 1:50,000 and will give an indication of inherent land stability.
Environment Canterbury has some records of surveys of hill and high country properties in its archives which may assist a qualified person to make an assessment of the general slope stability of an area. It is not possible to assess the stability of slopes at a property or site level without a professional interpretation of all available information including that held by Environment Canterbury.